Ion-Molecule Reaction of CO2+ with Butane and Isobutane at Thermal Energy

Article abstract of DOI:10.1246/bcsj.66.2864

Rate constants and product ion distributions have been determined for thermal energy reactions of CO⁺2 with n-C4H10 and i-C4H10 by using an ion-beam apparatus.The total rate constants are (9.8+/-2.0)*10^-10 and (1.0+/-0.2)*10^-9 cm³ s^-1 for n-C4H10 and i-C4H10, respectively.These values amount to about 75percent of the collision rate constants estimated from the Langevin theory.C4H⁺9, C3H⁺n (n=5-7), and C2H⁺n (n=3-5) are produced from n-C4H10 with branching ratios of 6, 56, and 38percent, while C4H⁺9 and C3H⁺n (n=5-7) are formed from i-C4H10 with branching ratios of 7 and 93percent, respectively.The lack of C2H⁺n fragments from i-C4H10 is attributed to a low probability of significant rearrangement of chemical bonds for the formation of the C2H⁺n fragments.The product ion distribution in the CO⁺2/n-C4H10 reaction is in good agreement with that predicted from the fragmentation pattern of n-C4H⁺10 at 13.78 eV, indicating that the CO⁺2/n-C4H10 reaction proceeds through a near-resonant charge transfer without momentum transfer.